Formation of substituted phenalenes from the Birch reduction of pyrene and perylene.

Abstract

The Birch reduction of pyrene and perylene was investigated under a variety of conditions. 1. The reduction of pyrene (1) with four equivalents of sodium in liquid ammonia in the presence of ethanol (ether was used as a co-solvent) gave 89% of a mixture of 1,2,3,6-tetrahydropyrene (2) and 1,2,3,5-tetrahydropyrene (3) (in a ratio 2:1), 8% 1,2,3,3a,4,5,5a,6,7,8-decahydropyrene (5) and 3% recovered pyrene. 2. The reduction of pyrene with two equivalents of sodium under the same experimental conditions as [1] gave 45% tetrahydropyrenes (2 and 3), 2% decahydropyrene (5) and the balance was recovered pyrene. 3. The protonation of pyrene anion (prepared from pyrene with two equivalents of sodium in liquid ammonia - ether used as co-solvent) with ethanol or t-BuOH gave 30% tetrahydropyrenes (2 and 3), 10% 4,5-dihydropyrene (12) and the balance was recovered pyrene. 4. The protonation of pyrene anion (prepared as in [3]) with water gave 55% 1, 2-dihydropyrene (16), 5% 4,5-dihydropyrene (12) and the balance was recovered pyrene. 5. Methylation of the above pyrene anion gave 4-methylpyrene (76) and 2-methylpyrene (78) in the ratio 3:1 respectively. 6. Reduction of pyrene (1) with lithium in ethylenediamine (modified Birch reduction) gave tetrahydropyrenes (2 and 3) as absolute products. (Abstract shortened by UMI.)